refactor(main.py): move grade directory creation to the point of use

main.py

@@ -76,11 +76,6 @@ class MediaGrader:
         self.window_width = 800
         self.window_height = 600
 
-        # Create grade directories
-        for i in range(1, 6):
-            grade_dir = self.directory / str(i)
-            grade_dir.mkdir(exist_ok=True)
-
     def find_media_files(self) -> List[Path]:
         """Find all media files recursively in the directory"""
         media_files = []
@@ -353,6 +348,10 @@ class MediaGrader:
 
         current_file = self.media_files[self.current_index]
         grade_dir = self.directory / str(grade)
+        
+        # Create grade directory if it doesn't exist
+        grade_dir.mkdir(exist_ok=True)
+        
         destination = grade_dir / current_file.name
 
         counter = 1